He cleverly gets rid of Shishupal, making him exhuast the "100 mistakes I spare his life" promise he had given to the latter's mother. And earlier he had eloped with Rukmini who was betrothed to Shishupal, but had her heart on Krishna.
Durga (Shakti) is a ferocious, fearless, gutsy, brave warrior with never give up atittute. Once she has set her aim, she will never give up to achieve the aim..no matter what. She has killed the mighty demons like Mahishasur, Shumbha, Nishumba, Raktabeej ( killed by Kali - another form of Durga), Durgasur, Arunasur and so on.
It is saying that Durga also is capable of countering Shiva's trident if thrown it toward her. Another one warrior was Atikya (son of Ravana) who grabbed the trident mid air when shiva threw it toward him.
Whenever Durga / Kali becomes angry, no gods including supreme Brahma, Vishnu have the guts to go near her. Only Shiva can calm her down, not by coming in front of her to fight with her. He uses his mind how to calm her down. I am giving the samples...
Sample 1. He laid down among the corpses of demon and when Kaali (Durga) put her right foot on her, it made her shocked first and then she cooled down.
Sample 2. Shiva turned himself into a crying baby and when angry kaali saw the baby, she became compassionate and started loving the baby ( her anger was gone).
Sample 3. Once Shiva asked angry Kali to dance with him and Kali accepted. Both started dancing together. Kali matched every steps of lord shiva.
Then Shiva took a tricky step - "Urdhvatandava" which Kali refused because it was not befit her as a woman and she became calm.
Durga / Kali are fierce, invincible warrior and greatest fighter with very strong determination. Also she is the consort of another strongest character - Lord Shiva. Both relies on each other for the functionality of universe.